There is provided a clip device which excises a living body tissue in a body lumen by using an endoscope, and which ligates an excised site and performs hemostasis thereon. With regard to this type of endoscopic clip device and a medical clip used for the device (hereinafter, abbreviated as a clip), Patent Document 1 discloses a technique in which a distal end arrowhead hook of an operation wire disposed in a treatment instrument body is inserted into and connected to a connection member in a proximal portion of the clip. If the operation wire is drawn in a state where the arrowhead hook is inserted into the connection member, the living body tissue is ligated. If the operation wire is further strongly drawn in this state, a small diameter portion of the connection member is broken. Then, in a state where the living body tissue is ligated, the clip is caused to indwell the inside of the body lumen. The connection member has a pair of semi-cylindrical passage holes facing each other. These passage holes are spread, thereby causing the arrowhead hook to be pushed into and connected to the connection member.
The clip has a pair of arms facing each other, and the arms are closed so that distal ends of the arms move close to each other. The arms have a self-openable force. The arms are closed against this power, and are accommodated in a sheath. In this state, the arms are inserted into a forceps hole of an endoscope. If the arms reach the vicinity of the living body tissue, the arms are caused to protrude from the sheath, and are opened using an elastic restoration force. Thereafter, the operation wire is drawn, and the clip is pulled into the sheath again, thereby closing the arms. In this manner, the living body tissue can be gripped and ligated by the arms.
Here, when the living body tissue is ligated, an orientation in which the arms of the clip are closed needs to align with the living body tissue to a desired degree. Therefore, the operation wire is rotated to generate torques, thereby transmitting the torques to the clip via the arrowhead hook and the connection member. According to the device disclosed in PTL 1, if an operation unit body is rotated to generate the torques, the operation wire and the arrowhead hook are rotated in conjunction with the operation unit body. Furthermore, the connection member is rotated due to a frictional force generated between the arrowhead hook and the connection member. In this manner, a pushing tube and the clip are rotated to generate the torques, thereby enabling the orientation of the arms to be adjusted.
In addition, as an endoscope technique has been developed in recent years, in many cases, medical treatments have been increasingly performed, such as observation inside the body lumen by using the endoscope and excision of the living body tissue by using the endoscope. As a result, there are increasing demands for an endoscopic treatment instrument which can ligate the living body tissue and perform the hemostasis thereon after treatment. As a treatment technique using the endoscope is improved, it is expected that the treatment such as the hemostasis using the endoscopic treatment instrument is reliably completed in a limited space inside the body lumen.
As the clip used for this type of endoscopic treatment instrument, PTL 1 and PTL 2 respectively disclose examples as follows.
PTL 1 discloses a clip unit used for the above-described purpose. The clip mounted on the clip unit has a shape in which a plurality of arms intersect each other once on a proximal side. Since the clip has this shape, when the clip is pulled into the clip unit in a state where the clip protrudes outward from the clip unit (state illustrated in FIG. 3 in PTL 1), the clip is opened once (state illustrated in FIGS. 4, 5A, and 5B in PTL 1), and thereafter, the clip is closed (state illustrated in FIG. 6 in PTL 1).
PTL 2 discloses a clip device used for the above-described purpose. The disclosed clip mounted on the clip device has both a shape in which the plurality of arms intersect each other once on the proximal side, similarly to PTL 1 (FIG. 12 in PTL 2), and a shape in which the plurality of arms are terminated on the proximal side without intersecting each other (FIG. 1 in PTL 2).